Question: $ { \left[\begin{array}{rr}{1} & {-2} \\ {1} & {-2} \\ {2} & {2}\end{array}\right]+\left[\begin{array}{rr}{2} & {0} \\ {-1} & {2} \\ {4} & {4}\end{array}\right] = {?} } $
Solution: To find the sum of two matrices, add the corresponding items between each matrix. ${\left[\begin{array}{rr}{1}+{2} & {-2}+{0} \\ {1}+{-1} & {-2}+{2} \\ {2}+{4} & {2}+{4}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{3} & {-2} \\ {0} & {0} \\ {6} & {6}\end{array}\right]}$